1. Field of the Disclosure
The present subject matter relates to a medical needle assembly of the type commonly used in blood collection or withdrawal systems. More particularly, the present disclosure relates to a needle cover for use in a medical needle assembly according to the foregoing recitation.
2. Description of Related Art
Blood collection sets, in their most basic form, typically include a collection container for receiving blood from a donor and a tube that provides a flow path from the blood donor to the collection container, the tube terminating in a needle for withdrawal of blood from a donor or patient. The needle assembly typically includes a needle or cannula attached to a needle hub which allows for manipulation of the needle assembly by the phlebotomist, nurse, or other medical professional.
Such needles are commonly shielded with a removable needle cover. Shielding the needle protects the medical professional from inadvertent contact with the sharpened needle tip. Shielding the needle also protects the needle from damage during shipping and transport. Shielding also preserves the sterility of the needle prior to use and ideally maintains the integrity of a closed blood collection system by preferably providing a hermetic seal between the needle cover and needle assembly. The needle cover may also optionally provide assurance to the end user that the needle has not been tampered with.
Examples of needle assemblies including associated needle covers are provided in U.S. Pat. Nos. 4,402,682 and 4,496,352, both of which are hereby incorporated herein by reference. These patents disclose a needle assembly including a cannula attached to a base and to donor tubing. The needle covers are made of a plastic material, which forms a thermal bond with the base to provide a tamper evident seal. The needle covers described in the above-referenced patents also include an internal plug within the bore of the needle cover and located at the distal end of the needle cover. The plug is made of a resilient material and includes a pocket for enveloping and protecting the distal needle tip.
Another example of a needle assembly and associated needle cover is disclosed in U.S. Pat. No. 4,551,138, which is hereby incorporated herein by reference. The needle cover disclosed therein includes a hollow body made of a sterilizable plastic material. The needle cover includes a resilient “layer” made of a polymeric elastomer located near the proximal open end of the needle cover. The diameter of the cylindrical resilient layer at the proximal end of the cover has a diameter that is smaller than the diameter of the needle post engaged by the needle cover. The needle cover is placed over the needle and engages the post of the needle hub. According to U.S. Pat. No. 4,551,138, a hermetic seal is formed between the needle cover and the hub or post portion of the needle assembly.